Movable device for inspecting a production line partially submerged in an expanse of water, suitable for negotiating a curve in the production line, and associated installation and method

ABSTRACT

A device comprises an assembly for attaching to and moving on the production line. The attachment and movement assembly comprises at least two clamps that can be actuated selectively to clamp the production line, the attachment and movement assembly comprising an active mechanism for moving the clamps longitudinally relative to each other. The attachment and movement assembly comprises a tilting mechanism for tilting the clamps relative to each other, between a position in which they are parallel to each other and a position in which they are tilted with respect to each other. The tilting mechanism comprises a flexion bar capable of switching from a straight configuration in the parallel position of the clamps to a curved configuration in the tilted position of the clamps.

The present invention relates to a movable device for inspecting aproduction line intended to be partially submerged in a body of water,including:

an inspection support bearing at least one sensor capable of beingpositioned facing the production line;

an attaching and moving assembly for attaching to and moving on theproduction line, connected to the inspection support.

Such a device is in particular intended to inspect a production line ina fluid exploitation installation, in particular for hydrocarbons.

The production line is for example a flexible pipe (in particular asdescribed in the normative documents published by the American PetroleumInstitute (API), API 17J, 3rd edition—Jan. 1st, 2009 and API RP 17B, 3rdedition—March 2002). Alternatively, the production line is an umbilicalor a rigid pipe.

Such production lines are in particular used in deep waters in the oiland gas industry, and generally extend through a body of water between asurface installation and a bottom assembly. These production lines canalso extend between two surface installations.

These production lines, and in particular the flexible pipes, aregenerally provided with armors that ensure their axial tensile holding.The armors are outwardly protected by an outer sheath made from apolymeric material that prevents the saltwater from the body of waterfrom penetrating in contact with the armors. However, if the outersheath is deteriorated and/or pierced, the armors may come into contactwith saltwater, which can lead to accelerated corrosion.

Furthermore, in the case of flexible pipes, a polymeric pressure sheatharranged below the armors tightly delimits an inner circulation passagefor the fluid. Nevertheless, certain acid compounds contained in thefluid may spread through the pressure sheath and penetrate the annularspace between the pressure sheath and the outer sheath, in which thearmors are found, also promoting corrosion.

The aforementioned pipes further undergo very high axial tensile forces,in particular when the body of water in which the pipe is positioned isvery deep.

In this case, the upper part of the pipe near the surface assemblyreacts a very significant axial tension, which may reach severalhundreds of tons.

The axial tension not only has a high average value, but also permanentvariations depending on the vertical movements of the surface assemblyand the pipe, under the effect of the agitation of the body of watercaused by the swell or by the waves.

The axial tension variations may reach several tens of tons and repeatcontinually throughout the lifetime of the pipe. In 20 years, the numberof cycles may thus reach more than 100 million.

Over time, the armors are therefore subject to fatigue phenomena inparticular resulting from corrosion and mechanical stresses applied onthe pipe.

These phenomena, as well as other events, may in some cases lead to adeterioration of the properties of the pipe over time, in particularafter several years of use.

To that end, to verify the integrity of the pipe, it is known to performan on-site inspection of the pipe using a device moving on the pipe.This operation, limited in time, advantageously includes a visualinspection and optionally measures including an ultrasonic echography, adetermination of the magnetic fluxes leaving the pipe, and/or adetermination of the Foucault currents detected along the surface of thepipe.

This determination involves placing measuring sensors as close aspossible to the outer surface of the pipe and moving them regularly.

At shallow depths, divers can perform this type of inspection.

For greater depths, a device of the aforementioned type intended toperform a video, ultrasound and x-ray inspection is for exampledescribed in WO2010/105003.

For its placement, the device is submerged at a depth of several tens ofmeters below the surface, then is attached on the production line bymeans of a remotely controlled robot. The device then moves on theproduction line, in the body of water, to perform a measuring campaign.

The device follows the curvature of the production line owing to a veryreduced contact surface formed by two separated sets of wheels and afunctional play between the wheels and the production line. Thepositioning precision between the device and the production line issufficient for a video inspection as described in WO2010/105003.

Such a device is not, however, fully satisfactory for measurementsrequiring increased precision, in particular to perform integritymeasurements of the production line.

One aim of the invention is therefore to provide an inspection devicethat allows a minute and very stable inspection of a production linepartially submerged in a body of water, irrespective of the position ofthe device on the production line and irrespective of the curve of theproduction line.

To that end, the invention relates to a device of the aforementionedtype, characterized in that the attaching and moving assembly includesat least two clamps that can be selectively actuated so that it gripsonto the production line, each clamp delimiting a central passage oflongitudinal axis, capable of receiving the production line,

the clamps being longitudinally movable relative to one another alongthe production line, the attaching and moving assembly comprising anactive mechanism for moving the clamps longitudinally relative to oneanother;

the attaching and moving assembly including a mechanism for tilting theclamps relative to one another, between a position parallel to oneanother and a position tilted relative to one another

the tilting mechanism comprising a flexion bar able to go from astraight configuration, in the parallel position of the clamps to acurved configuration in the tilted position of the clamps.

The device according to the invention may include one or more of thefollowing features, considered alone or according to any technicallypossible combination(s):

the flexion bar is biased elastically toward its straight configuration;

the curve radius of the flexion bar in the curved configuration isgreater than 50 m;

the tilting mechanism comprises a jacket movable jointly with a firstclamp from among the clamps, the flexion bar being movable jointly witha second clamp from among the clamps, the flexion bar being mountedtranslatable in the jacket, between a position inserted in the jacketand a position removed from the jacket;

the inspection support is movable jointly with the first clamp and withthe jacket;

the jacket defines a housing for receiving the flexion bar, the flexionbar comprising a head for guiding the movement of the flexion bar in thejacket, with a cross-section complementary to the receiving housing ofthe jacket;

the flexion bar includes a rod, the jacket defining a housing forreceiving the flexion bar, with a section larger than that of the rod,the jacket including a guide sleeve of the rod, with a cross-sectioncomplementary to that of the rod;

the active longitudinal movement mechanism of the clamps relative to oneanother includes at least one longitudinal jack mounted on a first clampfrom among the clamps, the longitudinal jack including a rod deployableparallel to the flexion bar in the straight configuration, the rod beingmounted on a second clamp from among the clamps;

the active longitudinal movement mechanism of the clamps relative to oneanother includes a first longitudinal jack mounted on the first side ofthe clamps, and a second longitudinal jack, mounted on a second side ofthe clamps, the clamps being received in the space with triangularcross-section defined between the flexion bar, the first longitudinaljack, and the second longitudinal jack;

the longitudinal jack comprises a cylinder articulated on the firstclamp, the rod being articulated on the second clamp.

The invention also relates to a fluid exploitation installation in abody of water, including:

a production line deployed in the body of water, the production linehaving at least one curved region;

a device as defined above, attached to the production line by means ofat least one clamp of the attaching and moving assembly,

the device being movable on the flexible production line in the curvedregion, by passage of the flexion bar from its straight configuration toits curved configuration.

The installation according to the invention can comprise one or severalof the following features, considered alone or according to anytechnically possible combinations: the production line is a flexiblefluid transport pipe, a rigid fluid transport pipe, an umbilical or acable.

The invention also relates to a method for inspecting a production linein a body of water, the production line having a curved region, themethod comprising the following steps:

attaching a device as defined above, onto the production line by meansof the attaching and moving assembly;

movement of the device along the production line by movement of theclamps of the attaching and moving assembly,

inspecting the production line using the or each sensor;

the movement step comprising the passage from the curved region byrotation of the clamps relative to one another between their parallelposition and their tilted position, the rotation of the clampscomprising the deformation of the flexion bar from the straightconfiguration to the curved configuration.

The method according to the invention may comprise one or more of thefollowing features, considered alone or according to any technicallypossible combination: the movement step comprises the following phases:

attaching a second clamp relative to the production line;

releasing a first clamp onto the production line, the first clamp beingmobile jointly with the inspection support;

moving the second clamp away from the first clamp to raise the firstclamp and the inspection support jointly relative to the productionline;

attaching the first clamp onto the production line;

releasing the second clamp relative to the production line;

moving the second clamp toward the first clamp, the first clamp and theinspection support remaining immobile relative to the production line;

the inspection step comprises the radial movement of the sensor on theinspection support between a retracted idle position and a positiondeployed applied on the production line.

The invention will be better understood upon reading the followingdescription, provided solely as an example, and in reference to theappended drawings, in which:

FIG. 1 is a schematic view of the upper part of the first fluidexploitation installation including a flexible production line and amobile inspection device according to the invention, arranged in asplash zone;

FIGS. 2 and 3 are side views of the device of FIG. 1, the clamps of thedevice respectively being separated and brought closer to one another;

FIG. 4 is a top view of the inspection support comprising a plurality ofsensors capable of being positioned facing the production line;

FIG. 5 is a view of a detail of FIG. 4;

FIG. 6 is an elevation view of a mechanism for relative tilting of oneclamp relative to the other;

FIG. 7 is a bottom view of a detail of the mechanism of FIG. 6;

FIGS. 8 to 10 illustrate various tilted configurations of the clamps ofthe device relative to one another using the mechanism of FIG. 6;

FIG. 11 is a three-quarters front perspective view of a clamp of thedevice of FIG. 1, the clamp being closed;

FIG. 12 is a top view of the clamp of FIG. 11, the clamp being open;

FIGS. 13 and 14 are views similar to FIG. 11 and FIG. 12;

FIG. 15 is a perspective view of a clamping pad of the clamp of FIG. 11;

FIG. 16 is a top view of a clamping actuator of the clamp of FIG. 11, ina configuration separated from an attaching point;

FIG. 17 is a view similar to FIG. 16, in a grasping configuration of theattaching point;

FIGS. 18 to 19 are views illustrating an additional actuator forseparating of the band;

FIG. 20 is a view similar to FIG. 17 of another additional actuator forseparating of the band.

A first fluid exploitation installation 10 in a body of water 12 ispartially illustrated in FIG. 1.

The body of water 12 is for example a lake, sea or ocean. The depth ofthe body of water 12 at the installation 10 is for example between 50 mand 3000 m, or even 4000 m.

The installation 10 includes a surface assembly 14 and a bottom assembly(not shown) or two surface assemblies 14, and at least one productionline 16 partially submerged in the body of water 12 from the surfaceassembly 14.

“Production line” refers to a line installed between the surfaceassembly 14 and the bottom assembly and capable of conveying a fluid,and a distinction should be made with a construction line not yetinstalled. Indeed, there is a major difference between these two typesof lines, a deterioration of the production line being able to causesignificant human, material and ecological disasters. Indeed, theproduction fluid, namely crude oil and/or raw gas, generally circulatingin the production line is flammable and pressurized. Damage to the pipecan cause a fire or an explosion as well as contamination of thesurrounding environment. In contrast, if damage occurs on a constructionline, for example during installation, it is still possible to change itwithout harm occurring other than economic harm. The catching conditionsof a device onto a production line are therefore much more critical thanonto a construction line.

The installation 10 further comprises, according to the invention, amobile inspection device 18 intended to catch reversibly and to travelon the production line 16 to inspect said production line 16.

The surface assembly 14 is for example floating. It is advantageouslyformed by a surface naval support that may for example be a FloatingProduction, Storage and Offloading (FPSO) unit, or a Floating LiquefiedNatural Gas (FLNG) unit, a semisubmersible platform, which may forexample be a Tension Leg Platform (TLP), an unloading buoy, a floatingvertical column or a ship. In a variant, the surface assembly 14 is afixed rigid structure of the “jacket” type or an oscillating structuresubject to the seabed.

In this example, the production line 16 connects the bottom assembly toan upper point 19 on the surface assembly 14. The production line 16 istherefore partially submerged in the body of water 12 and has an uppersegment arranged in a volume of air, while passing through a splash zone20. This splash zone 20 for example extends up to a depth of about 5 mwith favorable sea conditions. Currents generated by the mass transportcaused by the swell are next present beyond the splash zone up to adepth of about 50 m.

The production line 16 is then a riser.

One variant consists of a production line 16 partially submerged in thebody of water 12 and for example connecting two surface assemblies 14(typically an unloading buoy and a FPSO). This is in particular the casefor production lines of the OOL (“Oil Offloading Line”) type.

The production line 16 here is a flexible line. In the example shown inFIG. 1, the production line 16 is a flexible pipe intended to transporta fluid, in particular hydrocarbons. It thus delimits a central aperture21 for the flow of a fluid. Such a pipe is for example described innormative documents API 17J and API 17B published by the AmericanPetroleum Institute (API), API 17J (3rd edition—Jan. 1, 2009) and API RP17B (3rd edition—March 2002). It includes an inner sheath confining thefluid in the central aperture, at least one tensile armor layer, and anouter sheath on which the mobile inspection device 18 catches andtravels.

In a variant, as specified above, the production line 16 here is anumbilical. An umbilical is a production line as defined in the normativedocuments published by the American Petroleum Institute (API), API17^(E) (4^(th) edition—April 2011). The umbilical comprises an outersheath containing at least one functional link such as a power cable, anoptical fiber cable and/or a hydraulic line or bundles of functionallinks maintained in a sheath.

Also in a variant, the production line 16 is a rigid pipe. It thencomprises at least one metal tube delimiting a central aperture 21. Themetal tube is formed in one piece or is formed by an assembly of tubessegments welded end to end.

In another variant, the production line 16 is a bundle of rigid risers,connected to one another by spacers to prevent them from colliding intheir lateral movements in the water.

The production line 16 defines an outer surface 22 onto which the mobileinspection device 18 catches and travels. It optionally includes atleast one curved region 23 intended to be inspected by the mobileinspection device 18.

In reference to FIGS. 2 to 4, the mobile inspection device 18 includesan inspection support 24 bearing sensors 25, in particular visible inFIGS. 3 and 4, and an assembly 26 for catching onto and traveling alongthe production line 16, including two catching clamps 28, 30. The mobileinspection device 18 further includes at least one float 31 shownschematically in FIG. 3.

The inspection support 24 includes a frame 32 defining a U-shapedopening 34, a rotary plate 38, bearing the plurality of sensors 25, anda travel mechanism 40 of each sensor 25 toward the production line 16.It advantageously includes tight boxes 41 for receiving controlelectronics of the sensors 25.

The frame 32 is intended to extend perpendicular to the local axis ofthe production line 16 around a central part of the opening 34, withaxis A-A′, capable of receiving the production line 16. The opening 34emerges laterally outward over the entire height of the frame 32, toallow the placement and removal of the inspection support 24 around theproduction line 16.

The frame 32 is made from metal. It has a bulk that can vary from 700 mmto 1500 mm in width and depth and between 1000 mm and 2000 mm in height.

The rotary plate 38 is mounted rotating about the axis A-A′. It iscapable of rotating the sensors 25 about the local axis of theproduction line 16 to orient them angularly relative to the productionline 16.

The travel mechanism 40 here comprises arms 43A for pressing the sensors25 against the outer surface 22, a guide 43B for longitudinal travel ofthe pressing arms 43A along the production line 16, and an actuatingdevice 43C, capable of moving the pressing arms 43A radially toward theaxis A-A′.

The travel mechanism 40 also comprises an actuating device 43D capableof moving the pressing arms 43A along the longitudinal movement guide43B and parallel to the axis A-A′.

The sensors 25 are nondestructive sensors. They for example include anultrasound sensor, magnetic field detector (magnetometers), an x-raytomography sensor, a guided wave sensor, a flat panel detector and/or aFoucault current detector.

The ultrasound sensor is intended to perform an echographic inspectionof the type described in patent application FR 3,031,186. It applies onthe outer surface 22 of the production line 16. The signal emitted bythe sensor is transmitted in the production line 16 through the outerwall and the analysis of the reflected signal in particular makes itpossible to determine information on the thickness of the outer wall, oreven on the content located inside the outer wall.

The magnetic field detector is capable of performing a magnetic fluxleakage (MFL) analysis. The detector includes an electromagnet capableof generating a magnetic field so as to magnetize the component to betested. In the presence of surface flaws resulting in particular fromcorrosion, erosion or cracking phenomena, the magnetic flux leaks and isdetected by the detector. This detector can in particular be a magneticfield sensor of the Hall effect sensor type. Such a method essentiallyapplies to ferromagnetic materials.

The x-ray detector makes it possible to record the radiation transmittedafter passing through an object. The data acquired during themeasurement acquisition can be collected along multiple orientations.Using these measurement acquisitions, a digital image can be calculatedand reconstructed mathematically, according to the principle of x-raytomography. This technique makes it possible to access the core of thematerial to assess the radiological absorption variations andcomposition differences thereof. It also allows a very fine location ofany heterogeneity, singularity present in an object, and verification ofthe assembly and positioning of complex mechanical assemblies.

The flat panel detector includes an x-ray source configured to emitX-photons intended to interact with the inspected production line 16.This x-ray source is advantageously a high-energy source, preferablygreater than 2 MeV. The flat panel detector also includes an X-photonreceiver configured to collect the X-photons emitted by the source afterinteraction with the production line 16 to be inspected. The flat paneldetector is preferably a flat panel.

The guided wave sensor is capable of inspecting the mechanical integrityof different component elements of the inspected production line 16remotely, up to several tens of meters away, in hard-to-reach or eveninaccessible zones.

The Foucault current detector (“eddy current testing” or ECT) is capableof measuring the absolute or relative impedance of a detector thatcomprises a conductive coil in which an alternating current circulates.This method makes it possible to detect surface flaws and flaws near thesurface, when the location and orientation of likely flaws is knownbeforehand.

Given the very small sensitivity surface (generally around several mm²)of ultrasound, flux leakage and Foucault current sensors, thecomprehensive inspection of the surface 22 requires sweeping the entiresurface 22 of the production line 16 to be examined. The number ofsensors intended to measure the same physical property is thereforegenerally greater than or equal to 2.

A high sweeping speed can be implemented to obtain an industriallysatisfactory examining speed.

The sweeping of the entire surface of the production line 16 is done bythe rotary plate 38 and the actuating devices 43C and 43D. The sweepingspeed can reach 150 mm/s on each of the two axes.

The pieces of equipment of the inspection support 24 are tight,independently of one another. In particular, the inspection support 24comprises a jack 43C and two brushless motors for the rotary plate 38and the vertical travel system 43D of the sensors 25. Thecontrol/command systems of these motors are contained in a tight box.

In one embodiment, the following masses can be obtained:

-   -   mass of a box: 40 kg, the inspection device 18 being able to        comprise several,    -   mass of the translation module: 75 kg    -   mass of the rotary plate 38: 86 kg and 46 kg stationary plate        guide    -   mass of the motor means of the rotary plate 38: 26 kg    -   mass of the frame 32: 430 kg.

Each sensor 25 is moved radially toward the axis A-A′ by means of thetravel mechanism 40 between a retracted idle position and a positiondeployed radially toward the production line 16, advantageously incontact with the production line 16. Each sensor 25 is further movablealong the axis A-A′.

Each float 31 is for example formed from foam, in particular PVC foam,or a metal reservoir, in particular made from steel.

In one example, the total volume of the floats 31 is greater than 1000liters, for example 1600 liters, to provide a maximum mass of 50 kg inthe body of water 12. This facilitates the connection with a remotelyoperated vehicle (ROV). This mass is about 300 kg in a volume of airwhen the device is intended to be operated up to depths of 2000 m and isabout 600 kg when the device is intended to be operated up to depths of4000 m.

The mobile inspection device 18 can also include one or several cleaningmodules (not shown) for the production line 16 before inspection.Indeed, over time, grime can become deposited on the production line 16,for example algae, mollusks or the like generally grouped together underthe term marine incrustation. The cleaning module(s) can in particularinclude one or several nozzles coupled to one or several pumps to spray,against the production line 16, one or several high-pressure jets, forexample of freshwater, but potentially seawater directly suctioned onsite.

The cleaning module(s) may alternatively or in combination include oneor several nozzles coupled to one or several marine pumps to spray, onthe surface of the production line 16, one or several cavitation jetsfor example of freshwater, but preferably of seawater.

The cleaning module(s) may also or alternatively include rotary brushesintended to brush the production line 16.

One or several cleaning modules can be arranged upstream and/ordownstream from the inspection support 24.

The cleaning module(s) can include one or several deflectors arrangedupstream and/or downstream from the inspection support 24, saiddeflector(s) being configured to move the grime loosened from theproduction line 16 away from the sensors 25 in order to avoid anyinterference in the measurement acquisition.

In general, the total mass of the mobile inspection device 18 variesdepending on whether the device bears one or several sensors 25 and oneor several cleaning modules. The total mass of the mobile inspectiondevice 18 is in practice less than 3000 kg, preferably less than 2000kg.

In the example shown in FIGS. 2 and 3, the catching and travel assembly26 includes a first upper clamp 28, mounted stationary relative to theinspection support 24, a second lower clamp 30, mounted mobile relativeto the first clamp 28, and a mechanism 50 for longitudinal travel of theclamps 28, 30 relative to one another. According to the invention, thecatching and travel assembly 26 further includes a mechanism 52 fortilting the clamps 28, 30 relative to one another.

Each clamp 28, 30 is capable of selectively gripping the production line16. According to the invention, each clamp 28, 30 gripping theproduction line 16 is capable of individually bearing the mobileinspection device 18 so that it moves simultaneously in the body ofwater 12, on the surface of the body of water 12 in the splash zone 20,and outside the body of water 12, by reacting the weight of the mobileinspection device 18.

To that end, each clamp 28, 30 is capable of applying a clampingpressure on the production line 16. Clamping pressure refers to theaverage of the local pressures applied by the clamp 28, 30 on thecontact surface between said clamp and the production line 16.

As a simplification measure, a nominal clamping pressure is preferablycalculated. Nominal clamping pressure refers to the average of the localpressures applied by the clamp 28, 30 on a global surface Smcorresponding to the outer perimeter of the production line 16multiplied by the contact length of the clamp 28, 30 with the productionline 16.

This contact length will in particular be described more precisely inthe remainder of the description.

Thus, each clamp 28, 30 is capable of applying a nominal clampingpressure generally of between 2 bar and 90 bar, and advantageously ofbetween 2 bar and 40 bar. Preferably, and in order for the mobileinspection device 18 to be able to adapt and move over a large number ofdifferent production lines 16, in particular to adapt and move overflexible pipes, while respecting the most conservative standards, eachclamp 28, 30 is able to apply a nominal clamping pressure of between 10bar and 40 bar.

The nominal clamping pressure applied on the production line 16 by eachclamp 28, 30 is preferably less than 80 bar in order to limit the risksof damage of the production line 16.

In practice, the clamping pressure can be measured using a matrixpressure sensor. The matrix pressure sensor can for example becapacitive. The matrix pressure sensor generally assumes the form of aflexible film including an array of pressure sensors forming a mesh ofsaid flexible film and capable of providing information on the pressureapplied at each point of the mesh. The matrix pressure sensor isarranged over the entire perimeter of the production line 16, or acylindrical template with the same diameter as said production line,between said production line, or said template, and a clamp 28, 30. Theclamp 28, 30 is next actuated so as to grip the production line 16, orthe template, and thus apply a pressure on the matrix pressure sensor.The matrix pressure sensor then measures, at each point of the mesh, thepressure applied by the clamp 28, 30. The clamp 28, 30 is next loosenedfrom the production line 16, or the template, so as to release thematrix pressure sensor. It is next possible via software processing toaverage all of the pressures measured on the overall surface so as todetermine the nominal clamping pressure, etc.

The clamping force applied by each clamp 28, 30 is generally between 20kN and 1000 kN, preferably between 40 kN and 700 kN. In practice, theclamping force applied by each clamp 28, 30 is advantageously between 50kN and 200 kN to allow the inspection of the rigid pipes and umbilicalsand advantageously between 130 kN and 700 kN to allow the inspection ofboth the flexible pipes and rigid pipes and umbilicals.

The clamping force can be measured by the matrix pressure sensorpreviously described, using software processing making it possible toincorporate the set of contact pressures measured on the measuredcontact surface.

Such a nominal clamping pressure makes it possible to react the weightof the mobile inspection device 18 as it evolves in a volume of air, thepassage of the interface between the air and the water on the surface ofthe body of water 12, while being subject to the movements of the bodyof water 12, and the travel in the body of water 12.

The nominal clamping pressure applied by each clamp 28, 30 is chosen tocorrespond to the reacting of the weight of the mobile inspection device18 and hydrodynamic forces applied on said mobile inspection device aswell as to satisfy all of the issues previously mentioned and inparticular in play when the mobile inspection device 18 leaves the bodyof water 12 and is located in the splash zone. It is generally constant,irrespective of the position of the mobile inspection device 18, eitherin the body of water 12, or at the interface between the body of water12 in the air located above the body of water 12, or completely in theair above the body of water 12.

The weight of the mobile inspection device 18 can be completely orpartially offset by the floats 31 in the body of water 12. The nominalclamping pressure is then superabundant. It is also superabundant whenthe mobile inspection device 18 is located entirely in the air, but to alesser extent than when the device is located entirely in the body ofwater 12.

In another embodiment, the nominal clamping pressure is advantageouslyadapted to the position of the mobile inspection device 18 on theproduction line 16 and adjusted to be equal to the pressure necessary tomaintain the mobile inspection device 18 on the production line 16 inthis said position.

The aforementioned clamping pressure preferably applies over an areagreater than 200 cm², advantageously greater than 2000 cm² andpreferably between 1500 cm² and 8000 cm² over the outer surface 22 ofthe production line 16. This area then corresponds to the contactsurface between the clamp 28, 30 and the aforementioned production line16.

The actual contact surface between the clamp 28, 30 and the productionline 16 can be measured using a developer film of the Fujifilm Prescale,Extreme Low Pressure, 4LW R310 3M 1-E type, which becomes colored underthe effect of a pressure greater than 0.5 bar. The developer film isarranged over the entire perimeter of the production line 16, or acylindrical template with the same diameter as said production line,between said production line, or said template, and a clamp 28, 30. Theclamp 28, 30 is next actuated so as to grip the production line 16, orthe template, and thus apply a pressure on the developer film. Thesurface of the developer film thus becomes colored at each point wherethe pressure applied by the clamp 28, 30 is greater than 0.5 bar. Theclamp 28, 30 is next loosened from the production line 16, or thetemplate, so as to release the developer film. It is then possible tomeasure the colored surface of the developer film using differentmeasuring means, for example, an infrared area measuring device, animage acquisition device of the scanner type coupled to computerprocessing software for the image, etc.

This value is a reasonable approximation of the actual contact surfacebetween the clamp 28, 30 and the production line 16, and in any case alow value of said actual contact surface.

Another solution to measure the actual contact surface consists of usinga matrix pressure sensor identically to what was previously described,only the software processing varying and consisting of interpolating theactual contact surface rather than the nominal clamping pressure.

The clamping pressure is advantageously distributed around theproduction line 16, and advantageously applies over 30% or more of theperiphery of the production line 16, preferably over 70% or more of theperiphery of the production line 16. This limits the risks ofdeformation of the section of the production line 16. The ratio betweenthe perimetric contact length of each clamp 28, 30 on the productionline 16 and the perimeter of the clamp 28, 30 at the contact with theproduction line 16 is advantageously at least equal to 0.3, preferablyat least equal to 0.7.

Each clamp 28, 30 thus defines a contact surface with the productionline 16 with a length advantageously of between 150 mm and 600 mm,preferably between 300 mm and 500 mm, taken along the local axis of theproduction line 16 in the clamp 28, 30. This length is more generallyless than 0.8 times the outer diameter of the production line 16.

The axial component of the vertical clamping force opposing the weightof the mobile inspection device 18 is generally between 20 kN and 80 kN,preferably between 20 kN and 50 kN.

Advantageously, the Applicant has developed a model for calculating theminimum axial component to be reacted in particular involving:

-   -   the weight of the mobile inspection device 18 in the air;    -   the following hydrodynamic forces:        -   the Buoyancy Force, which depends on the submerged volume of            the mobile inspection device 18;        -   the inertia force during the movement of the mobile            inspection device 18;        -   the wave damping forces;        -   the drag force of the mobile inspection device 18 in the            water;        -   the wave excitation forces;        -   the slamming forces (in particular of the waves crashing on            the mobile inspection device 18);        -   the water exit force;        -   the forces exerted by the production line 16 on the mobile            inspection device 18 related to the movement of the            production line 16 connected to the fluid exploitation            installation 10, the latter being subject to hydrodynamic            forces connected to the swell.    -   safety coefficients.

It emerges from the model, in light of the orders of magnitude of weightand volume of the mobile inspection device 18, as well as sea conditionsfor which the mobile inspection device 18 is intended to operate (swellheight Hs less than or equal to 3 m), that the minimum axial componentto be reacted is equal to the product of a reaction coefficient β of thehydrodynamic forces resulting from the hydrodynamic model multiplied bythe weight of the mobile inspection device 18. In an adequateapproximation, the coefficient β is generally between 1.7 and 2.7depending on the desired sea conditions and a more or less severe choiceof the safety coefficients. Optimally, the coefficient β isadvantageously between 2 and 2.4, preferably equal to 2.25.

Thus, the radial clamping force is advantageously calculated using theformula:

(β×Fc)/f

The clamping pressure is advantageously calculated using the formula:

(β×Fc)/(f×Sc)=(β×Fc)/(f×2×π×a×Rc×Lc)

where β is the coefficient for reacting hydrodynamic forces resultingfrom the hydrodynamic model, Fc is the axial load, taken to be equal tothe weight in the air of the mobile inspection device 18, f is thesignificant friction coefficient, Sc is the contact surface between theclamp 28, 30 and the production line 16. To calculate the surface Sc, ais the ratio between the perimetric contact length of each clamp 28, 30on the production line 16 and the perimeter of the clamp 28, 30 at thecontact with the production line 16, Rc is the outer radius of theproduction line 16, and Lc is the length of the clamp 28, 30, takenalong the local axis of the production line 16.

Identically, the nominal clamping pressure is advantageously calculatedusing the formula:

(β×Fc)/(f×Sm)=(β×Fc)/(f×2×π×Rc×Lc)

Where Sm is the global surface.

The value of a is advantageously at least equal to 0.3, preferably atleast equal to 0.7 for the clamps 28, 30 according to the invention.

The significant friction coefficient f is calculated as follows. For theflexible pipes, the coefficient f is generally taken to be equal to thefriction coefficient between the outer sheath and the armors, which isgenerally lower than the friction coefficient between the surface of theclamp 28, 30 and the outer sheath. The smaller of the two coefficientsis generally chosen. The value of f is generally chosen between 0.05 and0.5, for the flexible pipes preferably 0.07, advantageously 0.3.

For the rigid pipes and the umbilicals, the coefficient f is generallytaken to be equal to the friction coefficient between the surface of theclamp 28, 30 and the outer surface 22 of the production line 16. It ischosen between 0.2 and 0.9 for the rigid pipes and the umbilicals,advantageously chosen to be equal to 0.3.

Examples of minimum nominal clamping pressure and clamping forces forflexible pipes, with a contact surface length of the clamp 28, 30 withthe production line 16 of 400 mm, are given in the table below:

Friction coefficient 0.07 0.3 Clamping force (kN) 631 147 Diameter ofthe production Nominal clamping line 16 (m) pressure (bar) 0.46 (18″)11.0 2.6 0.35 (14″) 14.1 3.3 0.25 (10″) 19.8 4.6 0.15 (6″) 32.9 7.7

Examples of minimum nominal clamping pressure and clamping forces forrigid pipes or umbilicals, with a contact surface length of the clamp28, 30 with the production line 16 of 400 mm, are given in the tablebelow:

Clamp 28, 30 Steel Aluminum Steel Steel material Outer surface SteelSteel Polyethylene Polyethylene material production line 16 Frictioncoefficient 0.25 0.45 0.3 0.8 Clamping force (kN) 177 98 147 55 Diameterof the production line 16 (m) Nominal clamping pressure (bar) 0.46 (18″)3.1 1.7 2.6 1.0 0.35 (14″) 4.0 2.2 3.3 1.2 0.25 (10″) 5.5 3.1 4.6 1.70.15 (6″) 9.2 5.1 7.7 2.9

In the example shown in FIG. 11, each clamp 28, 30 includes a frame 60,and a mechanism for opening the frame 60 (not shown).

Each clamp 28, 30 further comprises a plurality of contact pads 62 withthe production line 16, defining a central passage 63 for insertion ofthe production line 16, with axis B-B′, a belt 64 for clamping the pads62, a clamping actuator 66, capable of tightening the belt 64 and,according to the invention, a mechanism 68 for radial separating of theclamping actuator 66.

The frame 60 includes two rigid frame segments 72, 73, articulatedrelative to one another around an axis C-C′ parallel to the axis B-B′ ofthe passage 63. The frame segments 72, 73 are each in the shape of a C.

The frame 60 defines, on a first frame segment 72, a first articulationpoint 74 of the actuator 66 around an axis D-D′ parallel to the axisB-B′.

The rigid frame segments 72 are immobile relative to one another aroundthe axis C-C′ between an open configuration shown in FIG. 12, and aclosed configuration shown in FIG. 11.

The mechanism includes a jack mounted on one of the rigid frame segmentsand a connecting rod connecting the jack to the other of the framesegments 73. In a variant, the mechanism includes a hydraulic torquekey.

In the example shown in FIGS. 11 to 13, the deployment of a rod of thejack causes the closing of the frame 60, and the retraction of the rodcauses the opening of the frame 72 by rotating the second frame segment73 relative to the first frame segment 72.

To obtain a good distribution of forces, each clamp 28, 30 includes atleast three contact pads 62, advantageously at least five contact pads62, preferably at least seven contact pads 62. When the contact pads 62have a jaw 80 including a V-shaped contact surface, with an openingangle of between 120° and 170°, preferably of 150°, the number ofcontact pads 62 is advantageously equal to seven to provide a gooddistribution of the forces in the inspection range of 30 cm (12 inches)to 46 cm (18 inches) in outside diameter for the production line 16.

The contact pads 62 are mounted mobile in the frame 60, while beingconnected to one another by the clamping belt 64.

In reference to FIG. 15, each pad 62 includes a jaw 80 intended to comeinto contact with the production line 16, a guide support 82, receivingthe jaw 80 and optionally, one or several spacers 84 inserted betweenthe guide support 82 and the jaw 80 in order to position the jaw 80radially in the central passage 63.

Each pad 62 further includes at least one radial push element 86,capable of loosening the pad 62 from the production line 16, during theloosening of the clamp 28, 30.

The jaw 80 is preferably made from aluminum, which provides an optimalcompromise between mass, strength, manufacturing possibilities and cost.In a variant, other materials are used such as steel or titanium, apolymer, etc. The jaw 80 can include a contact surface that is planar,curved or V-shaped or that has any other shape suitable for one skilledin the art. When the contact surface is V-shaped, the opening angle ofthe V is advantageously between 120° and 170°.

The jaw 80 optionally includes a resilient coating. Preferably, theresilient coating is resilient along the radial component and is rigidalong the axial component. This prevents the movements of the mobileinspection device 18 in the vertical direction and maintains a goodprecision in the measurements.

In reference to FIG. 15, the jaw 80 defines a concave inner contactsurface 88 with the production line 16. It includes, radially facing theinner surface 88, rods 90 for mounting spacers 84 and for insertion inthe guide support 82.

The inner surface 88 is advantageously rough or striated.

The spacers 84 are engaged in the rods 90 behind the jaw 80.

In a variant that is not shown, the guide support 82 includes, on eitherside of the pad 62, at least one circumferential guide member protrudinglaterally relative to the jaw 80 in order to cooperate with the guidesupport 82 of an adjacent pad 62 and at least one housing for receivinga circumferential guide member of an adjacent pad 62.

Advantageously, the guide support 82 includes, on either side of the pad62, a plurality of circumferential guide members parallel to one anotherdefining parallel receiving housings between them.

Thus, during the clamping of the clamp 28, 30, the adjacent pads 62 arecapable of coming closer to one another laterally without travel alongthe axis B-B′, while being guided by the cooperation betweencircumferential guide members on a pad 62 and the correspondingreceiving housings on an adjacent pad 62.

In the example shown in FIGS. 11 and 15, each pad 62 comprises tworadial push elements 86 protruding on either side of the pad 62, at theaxial ends of the jaw 80.

Each radial push element 86 includes a rolling member 96 on theproduction line 16, radially mobile between a forward contact positionwith the production line 16, and a retracted position, and a member 98for elastically biasing the rolling member 96 toward the forwardposition.

During the clamping of the clamp 28, 30, the rolling member 96 iscapable of retracting by moving away from the axis B-B′, against theelastic biasing member 98. On the contrary, during the loosening of theclamp 28, 30, the elastic biasing member 98 moves away from the rollingmember 96 of the jaw 80, causing the loosening of the jaw 80 radiallyaway from the production line 16.

In this example, the rolling member 96 is a rotary roller. In a variant,the rolling member 96 is a ball rolling in a spherical cage. In stillanother variant, the rolling member 96 is replaced by a bearing member,such as a ski on a leaf spring.

The elastic biasing member 98 is capable of exerting a radial force ofseveral daN, for example between 1 daN and 50 daN.

Thus, the produced loosening is at least 0.1 mm, preferably at least 4mm, and may reach up to 100 mm or more.

The clamping belt 64 is for example made with a base of a flexible band100 arranged around the pads 62 to hold the pads 62. The flexible band100 arranged behind the pads 62 includes a first part 102 connected to afirst frame segment 72 and a second part 104 connected to a second framesegment 73. In order to avoid bending the flexible band 100 duringopening of the clamp , the first part 102 can be connected to the secondpart 104 using an articulated junction part. This articulated junctionpart can in particular take the form of a single or double hinge. Theconnection between the flexible band 100 bearing the pads 62 and theframe segments 72, 73 allows a radial play between them.

The flexible band 100 is generally made from metal, preferably made fromduplex stainless steel (for example grade 1.4462, E=200 Gpa, Rm=640 MPaat 20° C.) but can also be made from composite material. It has athickness of between 1 mm and 10 mm, preferably 4 mm, and a height ofbetween 100 mm and 600 mm, preferably greater than 300 mm.

The flexible band 100 is advantageously bent before mounting to give itthe initial shape.

In a variant, the clamping belt 64 includes several flexible bands 100with smaller dimensions relative to what has just been described.

The flexible band 100 is arranged behind guide supports 82 of the pads62, forming flexible hinges between the successive pads 62, to allow acircumferential movement of the pads 62 relative to one another.

The flexible band 100 is simply pressed behind the supports 82. Screwheads 105 (CHC or the like, visible in FIG. 15) screwed in the supports82 on either side of the flexible band 100 prevent the pads 62 fromdetaching from the flexible band 100. During clamping, the flexible band100 slides inside a rail formed behind the guide supports 82 and thescrew heads. Preferably, the supports 82 each include at least threescrews.

The surface behind the guide supports 82 is preferably curved. Thesurface behind the guide supports 82 is advantageously straightened soas to favor the sliding of the flexible band 100 and advantageously tolimit the winch effect during clamping of said flexible band 100. Alayer of plastic favoring the sliding can also be installed behind theguide supports 82, between the flexible band 100 and the pads 62.

The clamping belt 64 is thus capable of being maneuvered jointly withthe frame 60 between the open configuration of FIG. 12 and the closedconfiguration of FIG. 11, in which it is loosened.

The second part 104 of the belt 64 further defines a second point 76capable of being grasped by the clamping actuator 66, to take the beltinto a clamping configuration around the production line 16, illustratedby FIG. 17.

To reach the unclamped configuration, the clamp 28, 30 reaches acircumference value with a diameter equal to the nominal diameter plusthe necessary play as described above (at least 0.1 mm, preferably atleast 4 mm and in particular up to 100 mm or more).

This loosened configuration is midway between the clamping configurationand the open configuration.

The second point 76 is for example defined on a longitudinal bar carriedby an end pad 62.

In reference to FIGS. 12 to 14 and 16 to 17, the clamping actuator 66 isformed by a jack including a chamber 110 and a grasping member 112deployable from the chamber 110.

The grasping member 112 includes, at its free end, a hook 114 intendedto grasp the second point 76.

The grasping member 112 is translatable along a travel axis in thechamber 110 between a deployed position, visible in FIG. 16, and aretracted position, visible in FIG. 17 to bring the second point 76closer to the first point 74 when the grasping member 112 has graspedthe second point 76.

The tightening actuator 66 is further articulated on the frame 60 aroundan axis D-D′ parallel to the axis B-B′ of the passage 63, the axis D-D′passing through the first point 74.

Thus, the chamber 110 and the grasping member 112 are movable jointly inrotation about the axis D-D′ between a grasping configuration of thesecond point 76 and a configuration radially separated from the secondpoint 76, to allow the closing respectively of the opening of the frame60 and the clamping belt 64.

The travel axis of the grasping member 112 is advantageouslyperpendicular to the axis D-D′.

In the grasping configuration (FIG. 17), the free end of the graspingmember 112 and the travel axis have come closer to the axis B-B′ of thecentral passage 63. On the contrary, in the radially separatedconfiguration (FIG. 16), the free end of the grasping member 112 and thetravel axis have moved further from the axis B-B′ of the central passage63.

According to the invention, the radial separating mechanism 68 includesat least a first cooperating member 120 by cam effect, movable jointlywith the grasping member 112, and a second cooperating member 122 by cameffect, capable of cooperating with the first cooperating number 120,the second cooperating member 122 being secured to the frame 60 and/orthe belt 64.

The radial separating mechanism 68 further includes an elastic biasingmember 124, capable of returning the grasping member 112 toward thegrasping configuration, and advantageously, a mechanical connectingmember 126 between the grasping member 112 and the first cooperatingmember 120.

In the example shown in FIGS. 11 and 12, the first cooperating member120 is a cam, preferably with an inclined profile. The secondcooperating member 122 is a cam follower, advantageously with a curvedprofile.

The slope of the curved profile is for example between 10° and 60°.

In a variant (not shown), the second cooperating member 122 is a cam,the first cooperating member 120 being a cam follower.

The mechanical connecting member 126 includes a lateral plate 128,mounted parallel to the translation axis of the grasping member 112. Theplate 128 is transversely connected to the grasping member 112, here bymeans of a bracket 129. It is guided along the chamber 110.

The first cooperating member 120 is mounted on the plate 128. Itprotrudes laterally relative to the plate 128, opposite the chamber 110,outside the frame 60.

The elastic biasing member 124 is articulated at a first end on an arm131 secured to the frame 60, and at a second end on the chamber 110. Itis for example formed by a helical spring.

The elastic biasing member 124 is capable of returning the second end ofthe elastic biasing member 124 into the vicinity of its first end tocause the grasping member 112 to pivot from the separated configurationto the grasping configuration.

In the deployed position of the grasping member 112, shown in FIG. 16,the first cooperating member 120 is placed in mechanical contact withthe second cooperating member 122. By cam effect, the mechanicalcooperation between the members 120, 122 pushes the chamber 110 towardthe axis B-B′ of the passage 63 and radially separates the free end ofthe grasping member 112 away from the axis B-B′ of the passage 63. Thisalso causes the extension of the elastic biasing member 124.

When the grasping member 112 retracts into the chamber 110, the inclineof the cam causes the progressive rotational travel of the free end ofthe grasping member 112 toward the axis B-B′.

From an intermediate position of the grasping member 112 between thedeployed position and the retracted position, visible in FIG. 17, thefirst cooperating member 120 ceases to cooperate by cam effect with thesecond cooperating member 122. The grasping member 112 then occupies itsgrasping configuration of the second point 74, up to the retractedposition.

In reference to FIG. 2, the longitudinal travel mechanism 50 includes atleast one longitudinal jack 140 longitudinally connecting the clamps 28,30. In the example shown in FIG. 2, the longitudinal travel mechanism 50includes two longitudinal jacks 140 arranged laterally on either side ofthe clamps 28, 30.

Each longitudinal jack 140 comprises a cylinder 142 articulated on theframe 60 of the inspection support 24 and a rod 144 deployable from thecylinder 142. The deployable rod 144 is articulated on the lower clamp30 at its free end.

The travel of the rod 144 is generally greater than 100 mm, able toreach up to 0.5 m or more.

Each longitudinal jack 140 extends parallel to the axis B-B′ of theclamps 28, 30 when the clamps 28, 30 are parallel to one another.

The jacks 140 are substantially coplanar, the plane defined by the jacks140 being as close as possible to the axis of the production line 16 soas to distribute the forces on either side of the production line 16,for example at a distance of between 60 mm and 120 mm from the axis ofthe production line 16.

The jacks 140 are advantageously arranged in a plane containing or atleast as close as possible to the axis of the production line 16 inorder to balance the forces and limit the moments applied on theproduction line 16.

The plane defined by the jacks 140 is preferably inclined by one orseveral degrees relative to the axis of the production line 16, suchthat the moments around the axis A-A′ of the production line 16resulting from tangential forces of the jacks 140 on the clamps 28, 30cancel each other out. Indeed, the two ends of each of the jacks 140 aregenerally articulated on the clamps 28, 30 by means of swivel links, orpivot links. Thus, when the jacks 140 deploy, a risk remains of the jack140 tilting relative to the axis of the production line 16 andstretching to cause a rotation of one clamp 28, 30 relative to the otheraround the axis B-13′. If the second jack follows the movement initiatedby the first jack, the rotational movement will then be amplified.

This problem is resolved by pre-inclining the jacks 140, such that theycannot be inclined in concert, but their inclines generate, on theclamps 28, 30, moments with axis B-B′ that oppose one another and cancelone another out.

The longitudinal travel mechanism 50 is capable of moving the lowerclamps 30 relative to the upper clamp 28 in translation parallel to theaxis B-B′ of the central passage 63, coaxial with the axis A-A′ of theproduction line 16, between a closed position, visible in FIG. 3, and aseparated position, visible in FIG. 2.

The tilting mechanism 52 is capable of allowing a movement of the clamps28, 30 in rotation relative to one another around an axis perpendicularto the axis A-A′ of the production line 16 between a position parallelto one another, visible in FIGS. 2 and 3, and at least one positioninclined relative to one another, examples of which are visible in FIGS.8 to 10, for the passage of an inclined part 23 of the production line16.

In reference to FIG. 6, the tilting mechanism 52 includes a hollowjacket 150 and a flexion bar 152 protruding outside the hollow jacket150. The flexion bar 152 is able to go from a straight configuration, inthe parallel position of the clamps 28, 30, to at least one curvedconfiguration, in the inclined position of the clamps 28, 30.

The minimum curve radius of the production lines 16 on which the mobileinspection device 18 moves is advantageously 50 m.

The hollow sleeve 150 extends parallel to the axis B-B′ of the centralpassage 63, perpendicular to the frame 60 of the inspection support 24and behind the latter. The frame 60 is fastened on the hollow jacket150.

The upper clamp 28 also extends perpendicular to the hollow jacket 150.It is mounted stationary on the hollow jacket 150.

The hollow jacket 150 includes a tube 154 defining a housing 156 forcirculation of the flexion bar 152, and a lower guide sleeve 158,closing a housing 156 at its lower end to guide the flexion bar 152.

The flexion bar 152 includes a deformable rod 160, a guide head 162inserted in the housing 156, and fasteners 164 for fastening the lowerclamp 30.

The deformable rod 160 has an outer diameter smaller than the innerdiameter of the housing 156 to delimit an annular space in the housing156. It has an outer diameter with a shape complementary to that of theguide sleeve 158.

The deformable rod 160 preferably has a hollow or solid circular sectionso as to allow flexion in all of the directions radial to the deformablerod 160. Indeed, depending on the position of the mobile inspectiondevice 18 on the production line 16, the flexion occurs in differentdirections (convex side, concave side or intermediate positions.

A circular section also gives good elasticity, so as to oppose therotation of one clamp 28, 30 relative to the other.

The deformable rod 160, when it is solid, has a diameter of between 10mm and 30 mm. When it is hollow, the deformable rod 160 has a thicknessof between 3 mm and 5 mm and an outer diameter of between 30 mm and 50mm.

The deformable rod 160 is made from metal, for example aluminum,stainless steel or titanium.

Advantageously, the deformable rod 160 is made from a material with aYoung's modulus E of less than 220 GPa, preferably less than 130 GPa,and an elastic limit Re advantageously greater than 300 MPa, preferablygreater than 1000 MPa.

The preferred material is titanium (E=105 GPa and Re greater than 1000MPa) for its greater elastic strength and its Young's modulus lower thansteel.

In a variant, the deformable rod is made from a composite material.

The guide head 162 protrudes radially relative to the rod 160. It has ashape complementary to that of the housing 156. It is capable of slidingin the housing 156 up to the guide sleeve 158.

The head 162 and the guide sleeve 158 are advantageously made fromplastic, for example high-density polyethylene to have a low frictioncoefficient and a low water absorption.

In the example of the figures, the fasteners 164 connect the lower clamp30 to a lower part of the flexion bar 152. The lower clamp 30 extendsperpendicular to the flexion bar 152.

The flexion bar 152 is translatable along the axis E-E′ of the hollowjacket 150, while being guided by the hollow jacket 150, during thetravel of the lower clamp 30 relative to the upper clamp 28.

Furthermore, the flexion bar 152 is able to go from a straightconfiguration, in the axis E-E′ of the jacket 150, to a curvedconfiguration, advantageously in the shape of an arc of circle.

In the straight configuration, the clamps 28, 30 are parallel to oneanother. The plane P1 perpendicular to the axis B-B′ of the centralpassage 63 of the clamp 28 is parallel to the plane P2 perpendicular tothe axis B-B′ of the central passage 63 of the clamp 30.

In the curved configuration, the flexion bar 152 has a curve radiusgreater than 50 m (which is the minimum curve radius of the productionline 16) and in particular between 50 m and infinity when the productionline 16 is rectilinear. The respective planes P1, P2 of the clamps 28,30 are inclined relative to one another by a non-nil angle smaller than3° and in particular between 0° and 3°, 0° being when there is no curve.

The resiliency of the flexion bar 152 is capable of bringing the freeedges of the clamps 28, 30, located facing the flexion bar 152, closerto one another relative to their parallel position (see FIG. 9) or onthe contrary moving them further away from one another relative to theirparallel position (see FIG. 8).

The flexion bar 152 is located behind the clamps 28, 30, substantiallymidway from the longitudinal jacks 140. The clamps 28, 30 are thusreceived in the space with triangular cross-section defined between theflexion bars 152, a first longitudinal jack 140, and a secondlongitudinal jack 140.

This prevents the relative rotation of the clamps 28, 30 about the axisE-E′ of the jacket 150. The flexion bar 152 acts as a spring that exertsa moment opposing the rotational movement and that tends to return theclamps 28, 30 into the same axis.

The operation of the mobile inspection device 18 according to theinvention, during an inspection campaign of the production line 16, willnow be described.

Initially, the mobile inspection device 18 is lowered into the body ofwater 12 from the surface assembly 14 or a ship separate from thesurface assembly 14.

The mobile inspection device 18 is advantageously coupled to anunderwater remotely operated vehicle (ROV) by means of an interface 160secured to the frame 60.

The mobile inspection device 18 is then brought into the vicinity of theproduction line 16. The clamps 28, 30 are opened.

To that end, the clamping actuator 66 is deactivated. The graspingmember 112 occupies its deployed position. The radial separatingmechanism 68 is active, the first cooperating member 120 thencooperating with the second cooperating member 122 by cam effect to keepthe grasping member 112 in its separated configuration.

The opening mechanism is operated to move the frame segments 72, 73relative to one another and open access to the central passage 63.

Then, the production line 16 is introduced into the opening 34 of theinspection support 24 and into the central passages 63 of the clamps 28,30.

The clamps 28, 30 are then closed. The opening mechanism is actuated tomove the frame segments 72, 73 into contact with one another again andclose the central passage 63 around the production line 16, asillustrated by FIG. 13.

During this passage, the second part of the belt 64 comes closer to thefirst part 102. The pads 62 are arranged around the outer surface 22 ofthe production line 16.

This being done, the grasping member 112 is moved toward the retractedposition in the chamber 110. During this travel, the grasping member 112gradually comes closer to its grasping configuration by relative travelof the first cooperating member 120 relative to the second cooperatingmember 122, and by retraction of the elastic biasing member 124.

When the grasping member 112 reaches its intermediate position, thefirst cooperating member 120 disengages from the second cooperatingmember 122 and the grasping member 112 then occupies its graspingconfiguration of the second point 76.

The hook 114 at the free end of the grasping member 112 engages on thebar at the second point 76 and gradually brings the second point 76closer to the first point 74.

The pads 62 then press radially on the outer surface 22 of theproduction line 16 and gradually grip the production line 16, applying aclamping pressure on the production line 16 as defined above.

The mobile device 18 being situated in the body of water 12, the floats31 provide buoyancy to the mobile inspection device 18.

The sensors 25 are then brought into contact with or into the vicinityof the outer surface 22 of the production line 16 by means of the travelmechanism 40. Optionally, the rotary plate 38 is rotated around the axisA-A′ of the production line 16 to allow an appropriate movement of thesensors 25 and/or sweeping of a circumference of the outer surface 22 bythe sensors 25.

This being done, the mobile inspection device 18 is moved along theproduction line 16. Starting for example from the position of FIG. 3, inwhich the clamps 28, 30 are brought closer to one another, and when themobile inspection device 18 must rise along the production line 16, theupper clamp 28 is loosened, while the lower clamps 30 remains clampedagainst the production line 16.

Each longitudinal jack 140 of the longitudinal movement mechanism 50 isthen activated to separate the upper clamp 28 from the lower clamp 30and to raise the upper clamp 28 and the inspection support 24 jointly toreach the configuration of FIG. 2.

During this travel, the flexion bar 152 gets out of the upper jacket150. The flexion bar 152 is guided on the one hand by the sliding of theguide head 162 in the housing 156, and on the other hand by the slidingof the rod 160 in the guide sleeve 158.

The upper clamp 28 is then clamped on the outer surface 22 of theproduction line 16 and the lower clamp 30 is loosened.

Each longitudinal jack 140 is then retracted to return the lower clamp30 into the vicinity of the upper clamp 28, as illustrated by FIG. 3.

The preceding actions are then repeated until the mobile inspectiondevice 18 reaches the desired position on the production line 16.

The flexion bar 152 flexes under the effect of the moving clamp 28, 30,which, by sliding/rolling along the production line 16, follows thecurve of the production line 16.

During the passage of a curved part 23 of the production line 16, whenthe flexion bar 152 is positioned at the concave side of the curved part23, the free edges of the clamps 28, 30 move away from one another andthe flexion bar 152 goes from its straight configuration to its curvedconfiguration, as illustrated by FIG. 8.

On the contrary, when the flexion bar 152 is positioned at the convexside of a curved part 23 of the production line 16, the free edges ofthe clamps 28, 30 come closer to one another and the flexion bar 152bends as shown in FIG. 9.

When the flexion bar 152 is positioned laterally relative to the concaveside and the convex side of the curved part 23, as illustrated by FIG.10, the upper clamp 28 is inclined relative to the lower clamp 30,without their free edges coming significantly coming closer together andthe flexion bar 152 bends.

When the mobile inspection device 18 is oriented perpendicular to theplane containing the concave side and the convex side, the flexion ofthe clamps 28, 30 is therefore done laterally instead of front to back(or vice versa). When the mobile inspection device 18 is in anintermediate position, the flexion of the clamps 28, 30 is done in anintermediate direction.

The presence of a flexion bar 152 arranged between the clamps 28, 30provides an easy passage for the curved parts 23 of the production line16, irrespective of the curvature configuration of the curved part 23,and the relative position of the clamps 28, 30 with respect to theproduction line 16, without significant rotation of the clamps relativeto one another about the axis E-E′ of the bar 152. The clamps 28, 30therefore remain placed facing one another, even inclined relative toone another.

The mobile inspection device 18 therefore moves efficiently on theproduction line 16, by adopting the configuration of the production line16. This is obtained via simple and inexpensive mechanical means, whichdo not require active and sophisticated control or substantialmaintenance. In particular, no rigid connection via a guideway or thelike exists between the two clamps 28, 30. The mobile inspection device18 adapts naturally to the curve of the production line 16, which guidesits movement.

When the mobile inspection device 18 reaches the surface of the body ofwater 12, its buoyancy decreases.

The nominal clamping pressure applied on the outer surface 22 of theproduction line 16 is generally between 2 bar and 90 bar, andadvantageously between 2 and 40 bar. Preferably, and in order for themobile inspection device 18 to be able to adapt and move over a largenumber of different production lines 16, in particular flexible pipes,while respecting the most conservative standards, the nominal clampingpressure applied on the outer surface 22 of the production line 16 isbetween 10 bar and 40 bar.

The clamping force applied by each clamp 28, 30 is thus between 20 kNand 1000 kN, preferably between 40 kN and 700 kN. In practice, theclamping force applied by each clamp 28, 30 is advantageously between 50kN and 200 kN to allow the inspection of the rigid pipes and umbilicalsand advantageously between 130 kN and 700 kN for the inspection of boththe flexible pipes and rigid pipes and umbilicals.

Thus, the mobile inspection device 18 moves easily at the interfacebetween the body of water 12 and the volume of air located above thebody of water 12, in the partial or total absence of buoyancy, whilebeing subject to the local movements of the surface of the body ofwater, in particular the waves and the swell.

The mobile inspection device 18 next moves above the surface of the bodyof water 12 to inspect the part of the production line 16 connected tothe surface assembly 14. This makes it possible to inspect the upperpart of the production line 16. This is advantageous in particular forflexible pipes, since it is possible to inspect the production line 16up to the stiffness, inside the I- or J-shaped guide tubes. This forexample allows an ultrasound inspection of the armor yarns into theendpiece of the production line 16.

Such an inspection is possible owing to the optimized clamping force ofeach clamp 28, 30, allowing stable catching even without buoyancy, witha relatively reduced spatial bulk and weight relative to a caterpillarsystem. Furthermore, the applied clamping pressure remains appropriatenot to exceed the load conditions on the production line 16, or damagethe outer surface 22 of the production line 16, in particular when thelatter is a flexible pipe.

The mobile inspection device 18 is therefore particularly versatile,since it can work in the body of water 12, on the surface of the body ofwater 12, and in a volume of air located above the body of water 12,without it being necessary to take special precautions, or maneuver themobile inspection device 18 specifically using a crane or other surfaceequipment. No outside assistance is necessary from the surface assembly14, which greatly limits the risk and preparation time of theinstallation 10.

Advantageously, the inspection of the production line 16 using themobile inspection device 18 can be done during the fluid transportthrough the production line 16, in particular in production.

The holding of the mobile inspection device 18 by the clamps 28, 30guarantees very stable positioning of the inspection support 24, toensure very precise integrity measurements of the production line 16 bymeans of the sensors 25.

In a variant, the clamp 28, 30 includes an additional actuator 210 forloosening of the belt 64, visible in FIGS. 18 and 19.

The additional actuator 210 includes an opening rod 212, a pivotingsupport 214 for articulating the rod 212 a first articulation point 216on the frame segment 72 or 73 and a mobile lever 218, connected on theone hand on the opening rod 212 and on the other hand on a pivot 220secured to a first point of the belt 64.

The additional actuator 210 further comprises at least one member 222for elastic biasing of the rod 212, to return the clamping belt 64 tothe loosened configuration.

The pivoting support 214 is mounted rotating about an axis parallel tothe axis B-B′. It defines a passage transverse to its rotation axis, inwhich the rod 212 is mounted sliding. Thus, the rod 212 is capable ofbeing rotated jointly with the pivoting support 214. It is capable ofsliding transversely relative to the sliding support 214 in thetransverse passage.

The mobile lever 218 is mounted pivoting about an axis 224 that isstationary relative to a frame segment 72, 73, parallel to the axisB-B′.

One end 226 of the rod 212 is articulated on one side of the lever 218relative to the rotation axis 224. The pivot 220 is articulated onanother side of the lever 218 relative to the rotation axis 224.

The elastic biasing member 222 is mounted about the rod 212. It isinserted between a surface of the support 214 and an opposite stop 228secured to the rod 212.

In the clamping configuration of the belt 64, as illustrated in FIG. 18,the pivot 220 is kept relatively close to the outer surface 22 of theproduction line 16. The belt 64 is then brought closer to the outersurface 22 of the production line 16.

In this configuration, the end 226 of the rod 212 is relatively closerto the support 214 and the length of the rod 212 protruding past thesupport 214 is maximal.

The elastic biasing member 222 is compressed between the support 214 andthe stop 228.

During the loosening of the belt 64, as illustrated by FIG. 19, theelastic biasing member 222 deploys by pushing the end 226 of the rod 212away from the outer surface 22 of the production line 16. This movementcauses the sliding of the rod 212 in the support 214 to decrease the rodlength 212 protruding past the support 214.

At the same time, the lever 218 is rotated about the axis 224, causingthe travel of the pivot 220 away from the outer surface 22 of theproduction line 16. This opens the belt 64.

A variant of an additional actuator 210 is illustrated by FIG. 20.

The additional actuator 210 illustrated by FIG. 20 differs from thatshown in FIGS. 18 and 19 in that the rod 212 is articulated on thepivoting support 214 without sliding relative thereto. The additionalactuator 210 further includes a second opening rod 213, the pivotingsupport 214 also articulating the second opening rod 213 at the samefirst fixed articulation point 216 relative to a frame segment 72, 73,parallel to the axis B-B′ and a mobile lever 219, connected on the onehand on the second opening rod 213 and on the other hand on a pivot 221secured to a second point of the belt 64.

The mobile lever 219 is mounted pivoting about an axis 225 that isstationary relative to a frame segment 72, 73, parallel to the axisB-B′. One end 227 of the rod 217 is articulated on one side of the lever219 relative to the rotation axis 225. The pivot 221 is articulated onanother side of the lever 219 relative to the rotation axis 225.

The operation of the second opening rod 213 is identical to that of thefirst opening rod 212.

In one variant, the lower clamp 30 is mounted stationary relative to theinspection support 24, and the upper clamp 28 is mounted mobile relativeto the lower clamp 30 by means of the mechanism 50.

In one variant, the number of clamps 28, 30 is greater than two.

The clamps 28, 30 shown in the figures are each provided without alongitudinal travel device along the axis B-B′, in particularcaterpillar, situated in the clamp 28, 30, in particular around thecentral passage 63.

In still another variant, the assembly 26 for catching onto andtraveling along the production line 16 comprises a clamp 28 providedwith at least three caterpillars, advantageously five caterpillars,preferably seven caterpillars. Each caterpillar assumes the form of anassembly of links on which contact pads with the production line 16 aremounted. The contact pads are preferably metallic, preferably made fromsteel or aluminum, but could be made from composite material. Eachcontact pad includes a contact surface intended to come into contactwith the production line 16. The contact surface can be smooth, rough orstriated.

Each caterpillar includes an inner contact surface with the productionline 16, defining the central passage 63 for insertion of the productionline 16, with axis B-B′. The inner contact surface of each caterpillaris defined by the set of contact surfaces of the contact pads of thecaterpillar that are oriented toward the inside of the central passage63. The inner contact surface of the caterpillars extends over a lengthadvantageously of between 0.6 m and 2 m, preferably between 1 m and 1.4m.

The clamp 28 comprises a support structure. For each of thecaterpillars, a reinforcing chassis is mounted movably on the supportstructure, in particular mounted radially movably relative to the axisB-B′ so as to be able to adapt the separation of the caterpillars to thediameter of the production line 16. The reinforcing chassis or chassescan be driven in their mobility using one or several hydraulic jackswhich, in addition to the radial travel of the reinforcing chasses, alsomake it possible to apply, by means of the caterpillars, a radialclamping pressure on the line 16 as described, calculated or measuredbeforehand.

Each reinforcing chassis is configured to guide a caterpillar and thusincludes one or several guide elements on which the caterpillar travels.In particular, the guide element(s) can assume the form of rollersmounted rotatably on a rigid body. Thus, the links of the caterpillarroll on the rollers as it moves around the rigid body of the reinforcingchassis. Each reinforcing chassis can also include a tension means ofthe caterpillar assuming the form of one or several tension rollers.

The caterpillars are each rotated around at least one motorized gearwheel, generally mounted freely rotating on the rigid body of thereinforcing chassis, and the teeth of which engage with the chain links.The motorisation of the gear wheel is provided using an electric orhydraulic motor.

The clamp also comprises an opening mechanism making it possible toretract a sufficient number of reinforcing chassis and caterpillarassemblies so as to allow the passage of the production line 16 from aposition located outside the central passage 63 to a position locatedinside the central passage 63.

In order for the measurements to be effective at the splash zone, theaxial movement of the mobile device 18 under the effect of the swell islimited.

To that end, the caterpillar is rigid, for example by being formed fromsteel links. The caterpillar clamp is advantageously provided with adevice allowing the rotational blocking of the motor shafts of thecaterpillar, when the caterpillar is stopped.

In a variant, the clamps 28, 30 have a structure different from thatillustrated by FIGS. 10 to 16. In particular, the clamps advantageouslyhave no mechanism 68 for radial separation of the grasping member 112.

Moreover, the clamps 28, 30 capable of applying a nominal clampingpressure of between 2 bar and 90 bar to the production line 16.

1. A movable device to inspect a production line intended to bepartially submerged in a body of water, including: an inspection supportbearing at least one sensor configured to be positioned facing theproduction line; an attaching and moving assembly configured to attachto and to move on the production line, the attaching and moving assemblybeing connected to the inspection support, attaching and moving assemblyincluding at least two clamps configured to be selectively actuated togrip onto the production line, each clamp delimiting a central passagehaving a longitudinal axis, the central passage being configured toreceive the production line, the clamps being longitudinally movablerelative to one another along the production line, the attaching andmoving assembly comprising an active mechanism configured to move theclamps longitudinally relative to one another, the attaching and movingassembly including a tilting mechanism configured to tilt the clampsrelative to one another, between a position parallel to one another anda position tilted relative to one another, the tilting mechanismcomprising a flexion bar configured to pass from a straightconfiguration, in the parallel position of the clamps to a curvedconfiguration in the tilted position of the clamps.
 2. The deviceaccording to claim 1, wherein the flexion bar is biased elasticallytoward its straight configuration.
 3. The device according to claim 1,wherein the curve radius of the flexion bar in the curved configurationis greater than 50 m.
 4. The device according to claim 1, wherein thetilting mechanism comprises a jacket movable jointly with a first clampfrom among the at least two clamps, the flexion bar being movablejointly with a second clamp from among the at least two clamps, theflexion bar being mounted translatable in the jacket, between a positioninserted in the jacket and a position removed from the jacket.
 5. Thedevice according to claim 4, wherein the inspection support is movablejointly with the first clamp and with the jacket.
 6. The deviceaccording to claim 4, wherein the jacket defines a housing for receivingthe flexion bar, the flexion bar comprising a head guiding the movementof the flexion bar in the jacket, with a cross-section complementary tothe receiving housing of the jacket.
 7. The device according to claim 4,wherein the flexion bar includes a rod, the jacket defining a housingreceiving the flexion bar, with a section larger than that of the rod,the jacket including a guide sleeve of the rod, with a cross-sectioncomplementary to that of the rod.
 8. The device according to claim 1,wherein the active mechanism includes at least one longitudinal jackmounted on a first clamp from among the at least two clamps, thelongitudinal jack including a rod deployable parallel to the flexion barin the straight configuration, the rod being mounted on a second clampfrom among the at least two clamps.
 9. The device according to claim 8,wherein the active mechanism includes a first longitudinal jack mountedon the first side of the clamps, and a second longitudinal jack, mountedon a second side of the clamps, the clamps being received in the spacewith triangular cross-section defined between the flexion bar, the firstlongitudinal jack, and the second longitudinal jack.
 10. The deviceaccording to claim 8, wherein the longitudinal jack comprises a cylinderarticulated on the first clamp, the rod being articulated on the secondclamp.
 11. A fluid exploitation installation in a body of water,including: a production line deployed in the body of water, theproduction line having at least one curved region; a device according toclaim 1, attached to the production line by the clamps of the attachingand moving assembly, the device being movable on the production line inthe curved region, by passage of the flexion bar from its straightconfiguration to its curved configuration.
 12. The installationaccording to claim 11, wherein the production line is a flexible fluidtransport pipe, a rigid fluid transport pipe, an umbilical or a cable.13. A method for inspecting a production line in a body of water, theproduction line having a curved region, the method comprising: attachinga device according to claim 1, onto the production line by the attachingand moving assembly; movement of the device along the production line bymovement of the clamps of the attaching and moving assembly, inspectingthe production line sing the or each sensor; the movement of the devicecomprising the passage of the curved region by rotation of the clampsrelative to one another between their parallel position and their tiltedposition, the rotation of the clamps comprising the deformation of theflexion bar from the straight configuration to the curved configuration.14. The method according to claim 13, wherein the movement of the devicecomprises: attaching a second clamp relative to the production line;releasing a first clamp onto the production line, the first clamp beingmobile jointly with the inspection support; moving the second clamp awayfrom the first clamp to raise the first clamp and the inspection supportjointly relative to the production line; attaching the first clamp tothe production line; releasing the second clamp relative to theproduction line; moving the second clamp toward the first clamp, thefirst clamp and the inspection support remaining immobile relative tothe production line.
 15. The method according to claim 13, whereininspecting the production line comprises the radial movement of thesensor on the inspection support between a retracted idle position and aposition deployed applied on the production line.